Smithsonian / USGS Weekly Volcanic Activity Report

New Activity Highlights

The Weekly Volcanic Activity Report is a cooperative project between the Smithsonian's Global Volcanism Program and the US Geological Survey's Volcano Hazards Program. Updated by 2300 UTC every Wednesday, notices of volcanic activity posted on these pages are preliminary and subject to change as events are studied in more detail. This is not a comprehensive list of all of Earth's volcanoes erupting during the week, but rather a summary of activity at volcanoes that meet criteria discussed in detail in the "Criteria and Disclaimers" section. Carefully reviewed, detailed reports on various volcanoes are published monthly in the Bulletin of the Global Volcanism Network.

On 16 May HVO reported ongoing deflation at Kilauea’s summit, where the lava lake continued to recede in the Overlook Crater; by the afternoon the caldera floor had dropped a total of almost 1 m since the onset of the lake drainage. The drop of the floor stressed faults around the caldera causing earthquakes as strong at M 4.4. HVO and National Park staff reported frequent ground shaking, and damage to roads and buildings. Phreatic explosions had ejected blocks up to 60 cm in diameter that were found in the parking lot a few hundred meters from Halema’uma’u Crater. Ash plume heights varied, but generally rose no higher than 1.2 km and drifted N. Lava continued to erupt from multiple vents at the NE end of the active fissure system at the Lower East Rift Zone (LERZ). Lava from fissure 17 advanced about 90 m. Weak spattering arose from fissure 18, and fissure 20 was again active.

At about 0415 on 17 May an explosive event (or a series of explosions) at Overlook Crater generated an ash plume that, according to the Washington VAAC, rose as high as 9.1 km (30,000 ft) a.s.l. and drifted NE. Ash fell in areas downwind, including in the Volcano Golf Course and Volcano Village. Subsequent gas, steam, and ash emissions rose to 3.7 km (12,000 ft) a.s.l. and drifted SW. Fissure 17 actively spattered, though its lava flow had nearly stalled. Fissures 18, 19, and 20 reactivated, and a new fissure (21) opened between fissures 7 and 3. A 50-100-m-wide depression with cracks formed parallel to the fissures between Highway 130 and Lanipuna Gardens, into which pahoehoe lava flowed from fissures 20 and 21. Fissure 22 opened just downrift of fissure 19.

On 18 May a robust gas-and-steam plume rose from Overlook Crater, punctuated by several minor ash emissions. At 2358 a short-lived explosion generated an ash plume that rose up to 3 km (10,000 ft) a.s.l. and drifted SW. Spattering continued from fissures 15, 17, 18, 20, 21, and 22, with pahoehoe lava flows being erupted from fissures 17, 18, and 20. Large fountains at fissure 17 ejected bits of spatter 100 m high. Lava flows from fissure 18 traveled almost 1 km SE, and a flow from fissure 15 crossed Pohoiki Road. A fast-moving lava flow (275-365 m per hour) emerged from fissure 20 and traveled SE, across Pohoiki Road. Gas emissions remained elevated in areas downwind of the fissure system; air quality was poor from gas emissions as well as smoke from burning vegetation. Earthquake locations had not moved farther downrift in the previous few days.

Small ash emissions from Overlook Crater occurred intermittently on 19 May. The eruption of lava and ground cracking in the area of Leilani Estates subdivision continued. Fissure 17 was weakly active after fountaining earlier in the day. Fissures 16-20 merged into a continuous line of spatter and fountaining; flows from this fissure 20 complex flowed 275 m/hour S. Two of the flows joined less than a 1.6 km from the ocean and continued to flow S between Pohoiki and Opihikao roads.

During 19-20 May there were two explosive eruptions from Overlook Crater, and several smaller ash emissions. Lava flows reached the ocean overnight (late on 19 May) along the SE Puna coast. On 20 May spatter was ejected from fissures 6 and 17, and fissure 20 produced significant lava flows. A ground crack opened under the E lava channel diverting lava into underground voids. Gas emissions tripled as a result of the voluminous eruptions from fissure 20. Photos take in the afternoon showed two ocean entries along approximately 1 km of coastline.

A small explosion at Overlook Crater at 0055 on 21 May produced an ash plume that rose around 2.1 km (7,000 ft) a.s.l. and drifted SW. Several smaller emissions throughout the day ejected abundant ash. Robust steam-and-gas plumes also rose from the crater. Lava fountains from fissure 22 fed a channelized lava flow that entered the ocean N of MacKenzie State Park. Spattering occurred at fissures 6, 17, and 19. Small ash emissions from Overlook Crater continued on 22 May. Lava continued to enter the ocean, though by the afternoon only one entry was active. Most of the LERZ activity shifted to the middle part of the fissure system. The Aviation Color Code remained at Red and the Volcano Alert Level remained at Warning.

Based on analyses of satellite imagery and model data, the Darwin VAAC reported that during 17-18 and 21-22 May ash plumes from Langila rose to altitudes of 2.1-2.4 km (7,000-8,000 ft) a.s.l. and drifted WSW, W, and WNW.

PVMBG reported that a phreatic eruption at Merapi began at 0125 on 21 May and lasted for 19 minutes, generating an ash plume that rose 700 m above the crater and drifted W. A six-minute-long phreatic eruption began at 0938 and produced an ash plume that rose 1.2 km above the crater. Ashfall from both events was reported in areas 15 km downwind. A third event, detected at 1750, lasted three minutes and produced a plume of unknown height. After the events one volcano-tectonic earthquake and one tremor event were recorded. The seismicity along with increased phreatic events prompted PVMBG to raise the Alert Level to 2 (on a scale of 1-4).

OVPF reported that the eruption at Piton de la Fournaise which began on 27 April from fissures at Rivals Crater continued through 22 May. Flowing lava was mostly confined to tubes, though spatter was ejected 20-30 m above the highest-elevation (and most active) vent of the three. Lava was weakly ejected from the lowest-elevation vent. CO2 concentrations at the summit were high. Inflation continued to be detected. Tremor levels had increased around 15 May but then began to steadily decrease on 18 May. Observers noted a significant decrease in activity on 19 May at the highest-elevation vent, and by 22 May was quiet; the main cone continued to spatter.

PVMBG reported that at 1719 on 19 May an event at Agung generated an ash plume that rose 1 km above the crater rim and drifted SE. The Alert Level remained at 3 (on a scale of 1-4) and the exclusion zone continued at a 4-km radius.

JMA reported that there were 13 events and 20 explosions at Minamidake crater (at Aira Caldera’s Sakurajima volcano) during 14-21 May. Tephra was ejected as far as 1.1 km from the crater, and ash plumes rose as high as 2.7 km above the crater rim. The Alert Level remained at 3 (on a 5-level scale).

Based on analyses of satellite imagery, wind model data, and notices from PVMBG, the Darwin VAAC reported that during 16-22 May ash plumes from Dukono rose to altitudes of 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted NW, W, and SW.

Volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, observed explosions during 12-14 May that sent ash plumes as high as 2.8 km (9,200 ft) a.s.l. Ash plumes drifted about 20 km SW on 13 May. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).

INSIVUMEH reported that beginning at 1400 on 17 May a lahar descended the Seca (Santa Teresa) drainage on Fuego’s W flank. The lahar was 25 m wide, 1 m deep, and carried trees and blocks 1.5 m in diameter. During 19-21 May explosions occurred at a rate of 5-8 per hour, and generated ash plumes that rose almost 1 km and drifted 10-20 km S, SW, and W. Some explosions were accompanied by rumbling audible more than 30 km away, and shock waves that vibrated structures in Morelia (9 km SW) and Panimaché (8 km SW). Incandescent material was ejected 200-300 m above the crater rim, and generated avalanches of material within the Seca, Ceniza (SSW), and Las Lajas (SE) drainages that reached vegetated areas. Ash fell in areas downwind including in Santa Sofía (12 km SW), Morelia, Panimaché I and II, and Finca Palo Verde. A lava flow 700-800 m long was active in the Ceniza drainage.

KVERT reported that during 13-15 May a thermal anomaly over Karymsky was identified in satellite images, as well as ash plumes drifting about 150 km SW on 14 May. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).

The Tokyo VAAC reported that on 15 May ash plumes from Shinmoedake (Shinmoe peak), a stratovolcano of the Kirishimayama volcano group, were identified in satellite images drifting S at an altitude of 7.6 km (25,000 ft) a.s.l.JMA noted that white plumes rose 100 m above the crater rim during 18-21 May. The Alert Level remained at 3 (on a scale of 1-5).

KVERT reported that a thermal anomaly over Klyuchevskoy was identified in satellite images during 13-14 May. Strong explosions began at 0315 on 15 May, and generated ash plumes that rose as high as 10.5 km (34,400 ft) a.s.l. The ash clouds lingered around Klyuchevskoy and surrounding volcanoes for about eight hours before gradually dissipating. Nighttime summit incandescence and a hot avalanche were noted. The Aviation Color Code was raised to Orange.

Observatorio Vulcanológico del Sur del IGP (OVS-IGP) and Observatorio Vulcanológico del INGEMMET (OVI) reported that explosive activity at Sabancaya was comparable to the previous week; explosions averaged 30 per day during 14-20 May. Seismicity was dominated by long-period events and signals indicating emissions. Gas-and-ash plumes rose as high as 1.9 km above the crater rim and drifted N and NW. The MIROVA system detected nine thermal anomalies, and on 19 May the sulfur dioxide gas flux was high at 3,147 tons/day. The report noted that the public should not approach the crater within a 12-km radius.

PVMBG reported that during 16-21 May gray-to-white plumes from Sinabung rose as high as 700 m above the crater rim and drifted in multiple directions. At 0900 on 20 May an event produced an ash plume that rose 700 m and drifted NW. An ash plume from an event later that day at 2122 rose 2.5 km and drifted W and NW. The Alert Level remained at 4 (on a scale of 1-4), with a general exclusion zone of 3 km and extensions of 7 km on the SSE sector, 6 km in the ESE sector, and 4 km in the NNE sector.

The RSS (Really Simple Syndication) feed is identical to the Weekly Volcanic Activity Report minus some features including the header information (latitude and longitude and summit elevation), the Geologic Summary, and a link to the volcano's page from the Global Volcanism Program. Each volcano report includes a link from the volcano's name back to the more complete information in the Weekly Volcanic Activity Report on the Smithsonian website.

The CAP (Common Alerting Protocol) feeds are XML files specifically formatted for disaster management. They are similar in content to the RSS feed, but contain no active links.

A Google Earth network link for the Weekly Volcanic Activity Report can be loaded into the free Google Earth software, and in turn will load placemarks for volcanoes in the current weekly report. Placemark balloons include the volcano name, report date, report text, sources, and links back to the GVP volcano page for that volcano and to the complete Weekly Report for that week.

Criteria & Disclaimers

Criteria

The Weekly Volcanic Activity Report does not necessarily include all volcanic activity that occurred on Earth during the week. More than a dozen volcanoes globally have displayed more-or-less continuous eruptive activity for decades or longer, and such routine activity is typically not reported here. Moreover, Earth's sea-floor volcanism is seldom reported even though in theory it represents the single most prolific source of erupted material. The Weekly Volcanic Activity Report summarizes volcanic activity that meets one or more of the following criteria:

- A volcano observatory raises or lowers the alert level at the volcano.
- A volcanic ash advisory has been released by a volcanic ash advisory center (VAAC) stating that an ash cloud has been produced from the volcano.
- A verifiable news report of new activity or a change in activity at the volcano has been issued.
- Observers have reported a significant change in volcanic activity. Such activity can include, but is not restricted to, pyroclastic flows, lahars, lava flows, dome collapse, or increased unrest.

Volcanoes are included in the "New Activity/Unrest" section of the Weekly Volcanic Activity Report if the activity occurs after at least 3 months of quiescence. Once a volcano is included in the "New Activity/Unrest" section, updates will remain in that section unless the activity continues for more than 1 month without escalating, after which time updates will be listed in the "Continuing Activity" section. Volcanoes are also included in the "New Activity/Unrest" section if the volcano is undergoing a period of relatively high unrest, or increasing unrest. This is commonly equal to Alert Level Orange on a scale of Green, Yellow, Orange, Red, where Red is the highest alert. Or alert level 3 on a scale of 1-4 or 1-5.

It is important to note that volcanic activity meeting one or more of these criteria may occur during the week, but may not be included in the Weekly Volcanic Activity Report because we did not receive a report.

Disclaimers

1. The Weekly Volcanic Activity Report is intended to provide timely information about global volcanism on a weekly basis. Consequently, the report is generated rapidly by summarizing volcanic reports from various sources, with little time for fact checking. The accuracy of the Weekly Volcanic Activity Report is dependent upon the quality of the volcanic activity reports we receive. Reports published in the Bulletin of the Global Volcanism Network are monthly, and more carefully reviewed, although all of the volcanoes discussed in the Weekly Volcanic Activity Report are not necessarily reported in the Bulletin. Because of our emphasis on rapid reporting on the web we have avoided diacritical marks. Reports are updated on the Weekly Volcanic Activity Report web page as they are received, therefore information may be included regarding events that occurred before the current report period.

2. Rapidly developing events lead to coverage that is often fragmentary. Volcanoes, their eruptions, and their plumes and associated atmospheric effects are complex phenomena that may require months to years of data analysis in order to create a comprehensive summary and interpretation of events.

3. Preliminary accounts sometimes contain exaggerations and "false alarms," and accordingly, this report may include some events ultimately found to be erroneous or misleading.

4. Many news agencies do not archive the articles they post on the Internet, and therefore the links to some sources may not be active. To obtain information about the cited articles that are no longer available on the Internet contact the source.

5. USGS Disclaimer Statement for this Website:

Information presented on this website is considered public information and may be distributed or copied. Use of appropriate byline/photo/image credit is requested. We strongly recommend that USGS data be acquired directly from a USGS server and not through other sources that may change the data in some way. While USGS makes every effort to provide accurate and complete information, various data such as names, telephone numbers, etc. may change prior to updating. USGS welcomes suggestions on how to improve our home page and correct errors. USGS provides no warranty, expressed or implied, as to the accuracy, reliability or completeness of furnished data.

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An RSS (Really Simple Syndication) feed for the Weekly Volcanic Activity Report first made available on 5 March 2008 can be utilized with the aid of various free downloadable readers. The report content of the news feed is identical to the Weekly Volcanic Activity Report minus some features including the header information (latitude and longitude and summit elevation), the Geologic Summary, and a link to the volcano's page from the Global Volcanism Program. Each volcano report includes a link from the volcano's name back to the more complete information in the Weekly Volcanic Activity Report on the Smithsonian website. On 12 March 2009, GeoRSS tags were added so that the latitude and longitude for each volcano could be included with the feed.

At the end of each individual report is a list of the sources used. We would like to emphasize that the World Organization of Volcano Observatories (WOVO) website (http://www.wovo.org/) lists the regional volcano observatories that have the most authoritative data for many of these events.

A Google Earth network link for the Weekly Volcanic Activity Report was first made available on 1 April 2009. This file can be loaded into the free Google Earth software, and in turn will load placemarks for volcanoes in the current weekly report. Placemark balloons include the volcano name, report date, report text, sources, and links back to the GVP volcano page for that volcano and to the complete Weekly Report for that week.